Broken Companies or Oversold Stocks?

Shares of U.S. investment bank Jefferies Group were down 20 percent at one point Thursday on concerns over the company's exposure to European sovereign debt, which were later explained in a press release.

"To be clear, as of August 31, 2011, Jefferies had no meaningful net exposure to European sovereign debt," wrote Peregrine Broadbent, Jefferies' CFO. He also notes that the combined exposure to euro-zone sovereign debt accounts to approximately $38 million, which amounts to about 1 percent of the company's shareholders' equity.

Despite today's moves, Jefferies stock had already lost more than 50 percent of its value so far this year.

Below is a look at some companies that have seen their shares deviate significantly from their 50-day moving averages and have lost more than 50 percent in price year-to-date.